Four-stroke engine

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An internal combustion engine in which the working cycle is completed in four strokes of the piston (i.e. in two revolutions of the crankshaft).

Note: The four strokes correspond to

1. Induction of the working fluid

  • air in diesel engines
  • fuel or fuel-air mixture in petrol engines

2. Compression of the working fluid

3. Fuel injection and combustion in diesel engines

  • fuel ignition and expansion of the ignited fluid in petrol engines, this stroke is the power stroke

4. Exhaustion of the waste gases

Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)

International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM